1. Field of the Invention
The present invention relates to a process for preparing a bacteriological inhibitor for water, particularly for drinking water.
2. Development of the Invention
In recent years, the source of water supply has been contaminated by a variety of chemicals, bacteria, other microorganisms, etc. due to overpopulation or industrial wastes and, for purpose of preventing such contamination, large amounts of chlorine have been used during water purification. Accordingly, tap water supplied to domestic places has a strong bleaching powder smell. Thus, a filter is usually employed to remove the bleaching powder odor. A princple of the filter is based on filtering capability of activated charcoal with which the filter is filled up and which exhibits strong deodoring effect. The thus treated water is indeed odorless. However, tap water which is supplied in a state where it contains residual chlorine and thus possesses a sterilizing power is desalted by activated charcoal and, as a result, looses its sterilizing power. In the case where such water that has lost its anti-bacterial power is retained in the filter, bacteria in the water abruptly proliferate using as nutrition sources trace organic constituents attached to the activated charcoal packed in the filter, and, the water becomes unpotable.
As a result of extensive investigations to eliminate such disadvantages in the prior art and develop a bacteriological inhibitor for water in place of activated charcoal, it has been found that sandy coral stone or coral sand (hereafter simply referred to as "coral sand") is extremely effective as a bacteriological inhibitor for water. Further, it has also been found that coral sand plated with silver greatly improves its sterilizing power. This silver-plated coral sand is prepared by desalting coral sand by washing roughly with water, subjecting to dry distillation, again washing roughly with water (for about 3 hours) and then plating the coral sand with silver. However, it has been found that considerably large amounts of nitric acid radicals (30 to 62 ppm) are detected from the thus prepared silver-plated coral sand.